1. Field of the Invention
The present invention relates to the maintenance of natural gas pipelines. More particularly, the invention relates to a device and method for transporting and delivering chemical to interior walls of pipelines.
2. Description of the Prior Art
The interior surfaces of pipelines over time become corroded by either by oxidation or other chemical reaction, particularly if the pipeline is made of metal. This creates a serious potential risk in the rupture of the pipeline. Deleterious liquids and solids can build up in the interior of the pipeline preventing maximum fluid carrying potential of the pipeline as well as corrosion to the pipe.
Over the past century, a number of different techniques have been developed for cleaning the interior of pipelines. A common practice is therefore been to periodically clean the interior of the pipelines by passing cleaning device known in the art as a “pig” therethrough.
The pig is disposed in the interior of a pipeline and is moved by gas or fluid flow through the pipeline. The pig is constructed with an exterior structure to scrub the interior wall of the pipeline to scrape or brush the interior to dislodge solid materials. For example, one type of cleaning pig is known as a “foam pig” made out of plastic foam, such as polyurethane foam. This type of pig is durable and relatively inexpensive compared to pigs having metal or rigid plastic bodies. Pigs can have brush bristles that normally extend above the pig body for cleaning the inner pipeline walls. However, in some cases, the bristles scratch the interior surface of the pipeline. Such pigs are primarily are used for removal of debris through mechanical means and prone to lodging within the pipeline. Attempts to solve the lodging of pigs include ways of lubricating the exterior when stuck.
Still another pipeline cleaning technique is to provide a plurality of ports in the pipeline through which a spray nozzle may be inserted to emit cleaning/treating chemicals. The disadvantage of this type of technique is that the chemicals typically do not uniformly cover the inner walls due to the nozzle limitations, wherein typically a stream of chemicals is sprayed through pipeline with uneven application along the length thereof and such chemicals come to rest in the bottom of the pipeline. Also, this technique does not remove relatively larger solids from the inner walls as a pig may do.
There remains a significant need to improve the way in which pipelines are maintained. The prior techniques fail to provide an adequate solution to chemically and mechanically clean and treat inner walls of pipelines. The present invention overcomes the above mentioned problems with the art.